The present invention relates to organophilic clay thickeners which are dispersible in non-aqueous fluids to thicken such fluids by forming a gel therein or otherwise modifying the viscosity of such fluids. The invention also pertains to a process for preparing these organophilic clay gellants, and to non-aqueous fluid compositions including the same.
It is well known that organic compounds containing a cation will react with a clay under favorable conditions by ion exchange to form an organophilic clay. Such clay modification results in a product which unlike clay is dispersible in non-aqueous fluids to change fluids characteristics such as viscosity. It is also known in the art that such organophilic clays can be used to modify the viscosity (thicken) of a variety of organic compositions including inks, greases, drilling fluids, paints and other similar products. See for example, U.S. Pat. No. 2,966,506 and the book Clay Mineralogy, 2nd Ed., 1968, R. E. Grim (McGraw Hill Book Company).
It is also well known that such complexes may function to thicken polar or non-polar petroleum based solvents, depending on the substituents on the organic salt. J. W. Jordan, in "Proceedings of the 10th National Conference on Clays and Clay Minerals" (1963), discusses a wide range of applications of organophilic clays.
In some situations the efficiency of organophilic clays can be further improved by adding a low molecular weight polar organic material to the composition. Such polar organic materials have been called dispersants, dispersion aids, solvating agents and the like. The most efficient polar materials for use as such have been found to be low molecular weight alcohol and ketones, particularly methanol and acetone. See for example U.S. Pat. Nos. 2,677,661, 2,704,276, 2,833,720, 2,879,229 and 3,294,683. The use of such dispersion aids has in other situations been found to be unnecessary when using specially designed organoclays. See U.S. Pat. Nos. 4,105,578 and 4,208,218.
Furthermore, U.S. Pat. Nos. 3,977,897, 4,382,868 and 4,464,274 describe the preparation of preactivated organophilic clay gellants, used to thicken organic compositions wherein the activators are admixed with the organophilic clays.
More recently, organophilic clay gellants have been developed which are the reaction products of smectite-type clays with organic cations and organic anion combinations. These gellants have the advantage of being effectively dispersible in particular organic compositions. An illustrative patent which describes such improved organophilic clay gellants is U.S. Pat. No. 4,412,018.
There is today a growing demand for products based on naturally occurring oils such as soybean oil, safflower oil, corn oil, palm oil and the like, to replace organic solvents based on petroleum derivatives such as toluene, xylene or mineral spirits. Such solvents have more beneficial properties from environmental standpoints and in many ways create more efficacious products.
Relatively large amounts of the organoclay compositions are needed to impart the required viscosity in such systems, especially in those containing natural occurring oils. It is therefore an objective of this invention to provide an efficient thickener to impart the required viscosity to non-aqueous coating systems, and in particular, to systems based on naturally occurring oils.